1. Field of the Invention
Present invention relates to the field of polymer chemistry in general, while, in particular it relates to manufacture of terpolymer having enhanced physical and mechanical properties due to changes in the newly produced terpolymer.
2. Description of Related Art
Until now, the main groups of polymers which have been used as bitumen modifiers in the prior art includes, thermosetting polymers, thermoplastic polymers, natural (NR) & synthetic rubbers, thermoplastic elastomer (TPE) and Evaloy® (RET). Each of the above groups has disadvantages which cannot be called as ideal one, for example: thermoplastic polymers are characterized by softening on heating and hardening on cooling. Polyethylene (PE), atactic and isotactic polypropylene (APP, IPP), polyvinylchloride (PVC), polystyrene (PS), . . . , etc, are the main polymers of this group. Thermoplastic polymers associate at room temperature with bitumen, increasing its viscosity; however they do not significantly confer any element of elastic deformation to bitumen and can separate when heated. Thermosetting polymers are not widely used, due to the high cost and special method of application.
Natural rubber (NR) and synthetic rubbers such as polybutadiene, styrene-butadiene rubber (SBR), etc, are sensitive to decomposition and oxygen absorption. They have a molecular weight too high to be directly dissolved in the bitumen and must be partially decomposed and mechanically homogenized.
Thermoplastic elastomers (TPE) such as Styrene-butadiene-styrene (SBS) and Styrene-Isoprene-Styrene (SIS) are physically dispersed in bitumen, but do not chemically react with the bitumen. Keeping a consistent dispersion often requires extra care and attention; this can be especially difficult if there is any delay in using of the material. Also the butadiene mid block in SBS is unsaturated which means it will oxidize in the pavement. Elvaloy® (RET) (DuPont) is a random terpolymer comprising ethylene, normal butyl acrylate and glycidyl methacrylate (GMA). GMA copolymers chemically react with asphalt to form a polymer linked-asphalt system. Elvaloy (RET) can only be used for asphalt (not bitumen alone) which means it has no mechanical strength by itself. Thus, a need exist for new bitumen modifier which avoid the above disadvantages.